Automatic wrapping machines

ABSTRACT

A package to be wrapped with a heat-sealable material and sealed is conveyed to a wrapping station, and after being wrapped and the outwardly extending ends of the wrapping material being folded under the package it is conveyed over a concave element so that a substantially flat-bottomed package will be supported on the heating element at the outer edges of the package where the layers of material are thicker and will be spaced from the heating element inwardly of such edges where the layers of material are thinner.

United States Patent Inventor Erik O. Vilen [56] Reference; Cited UNITED STATES PATENTS "1" 1,887,844 :1/1932 Malocsay 53/388 x Filed Aug. 26, I969 2,195,222 3/l940 Neumalr 53/33 Dlvlslon of ber. No. 632,959, Apr. 24, 1967,

2,676,445 4/l954 Kottmann 53/388 107 9 s l 53 388 pa e te 7, 2, 5 B0 ton r I Assignee Triangle Package Machinery Company Primary Exammer-Ther0n E. Condon Chicago, Ill. Assistant Exammer-Neil Abrams Attorney-Johnston, Root, O'Keeffe, Keil, Thompson &

Shurtleff ABSTRACT: A package to be wrapped with a heat-sealahle AUTOMATIC WRAPPING MACHINES material and sealed rs conveyed to a wrapping station, and

after being wrapped and the outwardly extending ends of the 6 7 Drawing Flgs' wrapping material being folded under the package it is con- U.S. Cl...l....... 53/388, veyed over a concave element so that a substantially flat-bot- 53/l84, 219/388 tomed package will be supported on the heating element at Int. CL. B65b 51/10 the outer edges of the package where the layers of material are Field of Search 7 thicker and will be spaced from the heating element inwardly 39: 2 l9/388 ofsuch edges where the layers ofmaterial are thinner.

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PATENTED AUBI 7 I97! SHEET 3 0F 3 INVENTOH. ERIK O. VILEN BRIEF SUMMARY OF THE INVENTION The invention is directed to an automatic wrapping machine for wrapping packages and is completely'automatic as distinguished from the semiautomatic wrapping machines wherein an initial wrap is performed by hand before placement in the machine. v

"In the machine a package is conveyed by an infeed conveyor and a crossfeed conveyor to a wrapping station consisting of a platform and an infeed pusher member. The infeed pusher pushes the package through a vertically hanging web of wrapping material onto-a table, whereupon the leading end of the wrapping material is positioned below the package and extends upwardly around the advancing edge of the package. The web of material is furnished from a roll located at one end of the machine and which initially positions the web from above the platform and table to a position therebelow, and the leading end thereof is held against movement until the package is pushed therethrough onto the table.

Thereafter, a folder bar normally positioned above the table is caused to move downwardly carrying withit the web of wrapping material until the folder bar reaches a gripper bar positioned below the table. A bight of the wrapping material, then, is gripped between the folder bar and gripper bar.

The table, with the package thereon, together with the film gripped between the folder bar and gripper bar, all move downwardly. A cutting edge is fixed between the table and platform and during the downward movement of the table a wedge or blade member wedges the web of material over the cutting edge andbehind it, so that a bight of the material is formed over the cutting edge. Continued movement downwardly of the table, package, folder bar and gripper bar with the material therebetween, causes the material to be cut by pulling it across the cutting edge.

When the lowering table reaches its lowermost position, the package is moved by an outfeed pusher from the lowering table onto a receiving table which thereupon causes a tucking of the wrapping material and causes the trailing end of the wrapping :material to be folded along the bottom of the package in overlapping relation with that portion of the leading end thereof which had theretofore been'brought against the package bottom. A slight movement upwardly of a pair of spaced downfolder supports lifts the package above the receiving table which will cause the outwardly extending ends of the wrapping material to be partially folded downwardly, whereupon a continuously moving conveyor moves the package through and beyond stationary plows to fold the remaining ends of the wrapping material upwardly against the bottom of the package. The package is then conveyed to a heating element to seal the ends of the wrap against the bottom of the package. In the event the wrapping material used is heat shrinkable, then the package will further be conveyed through a heat tunnel to shrink the material about the package.

The principal object of this invention is to provide in a package-wrapping machine a novel heat-sealing device for sealing the underfolded ends of a heat-scalable wrapping material against the bottom of the package.

Other objects and advantages of the invention will become apparent upon reading the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a vertical, longitudinal sectional view through the machine;

FIG. 2 is a fragmentary, perspective view of apart of the machine showing the outfeed conveyor and plows, as well as the conveyor which carries the package over the heat-sealing device, and looking in the direction away from said device FIG. 2a is a fragmentary, perspective view of a detail to illustrate it more clearly than may be seen in FIG. 2;

FIG. 3 is a fragmentary, perspective view of the heat-sealing station with certain parts broken away for the sake of clarity, and looking in the direction away from the conveyor;

FIG. 4 is an enlarged perspective view of a detail of the heat-sealing device shown in FIG. 3

FIG. 5 is an end .elevational view of the heat-sealing device taken along the plane of line 5-5 of FIG. 3, and

FIG. 6 is a transverse sectional view of the heat-sealing device taken along the plane of line 6-6 of FIG. 3.

DETAILED DESCRIPTION Referring now more particularly to the drawings, and especially to FIG. 1 there is shown a wrapping machine which embodies the features of the present invention as it is intended to be associated with other parts of the machine so that a package may be wrapped and sealed automatically. The wrapping machine is indicated generally by the numeral 1 while the numeral 2 illustrates in general the location of the sealing station which heat seals the wrapping material on the bottom of the package. In the event the wrapping material being used is heat shrinkable, there is provided a heat tunnel generally indicated at 3 through which the package passes and which has the interior thereof heated to an appropriate temperature for shrinking the wrapping material about the package.

The machine consists of a frame generally indicated by the numeral 15 which comprises the spaced bottom angle members 16 which extend longitudinally of the machine. Upright bracing end members 17 and 18 extend upwardly from the lower side members 16 and the frame is supported by the legs 19 and 20 at each side of the machine. The uprights l7 and 18 are connected by another longitudinally extending angle member at the top thereof, and other suitable intermediate bracing and support members may also be provided, as may be desired. i

A main drive shaft 24 extends transversely of the frame and is journaled in suitable bearings at the ends thereof. The drive shaft is driven by a motor (not shown) through suitable gear reduction means. The drive shaft 24 has several cams spaced along the length thereof, all of which are driven to impart certain mechanical movements to achieve the endresults.

The details of operation of the machine in general are described in the aforesaid U.S. Pat. No. 3,486,294, but for purposes of the present invention it is sufficient to state that in the general operation of the machine a package P is moved across a platform 27, through the downwardly extending web of wrapping material W and onto a lowering table 69. The material is moved downwardly behind the package P-by the lowering of a bar 158 and is automatically cut. When the table is lowered a pusher member pushes the package onto a receiving table 201.

When the package P is pushed from the platform 27 onto the lowering table 69, the web of wrapping material will extend along a portion of the package bottom and up over the leading edge of the package. There will also be ends of the wrapping material extending outwardly beyond the ends of the package. Provision is made for tucking the web along each end ofthe package as it is moved onto the table and for folding downwardly those ends as the folder bar 158 folds the material downwardly over the trailing edge of the package.

There is also provided a pair of downfolder arms 199 positioned immediately above the tuckers and which are. normally in an elevated position as shown in FIG. 1.

Each downfolder arm 19-9 has extending downwardly from the rear end thereof, an arm 200 which, together with the arm 199, forms a bell crank lever which'is rotatable about the rod 149 as well as slidable along the length thereof.

As the'package is receivedonto the lowering table 69 and reaches its proper positions thereonthe rocker arms 163 will move rearwardly, as in said aforementioned patent and willthus not only cause the folder-bar 158 to move downwardly, but will also allow the downfolder arms 199 to move downwardly, which sill thereupon cause the wrapping material which extends beyond each end of the package, to be folded downwardly onto the top of the lowering table.

Also during movement of the package onto the receiving table 201, the front portions of the material extending beyond the ends of the package will be tucked along the ends thereof by the tuckers 204 positioned at each side of the center of the machine, as may be seen more clearly in FIG. 2.

Each tucker is mounted on a downfolder support 205, one located at each side of the machine center and each of which is mounted at the upper end of a supporting plate 206. Initially when the package is moved onto the receiving table 201, the downfolder supports 205 are in a lowered position at the same level as, or slightly below, the receiving table rails 202 and 203. At this point the web will have been wrapped beneath the package and the ends thereof tucked along the ends of the package by the tuckers 204. The downfold supports 205 are then caused to move upwardly above the rails 202 and 203 to perform a partial downfolding of the extending ends of the web or wrapping material.

The package is then caused to move by means of an outfeed conveyor onto the belt conveyor 276 where the sealing of the package takes place. As the package is thus moved, the extending ends of the wrapping material which have been partially folded downwardly, will be located outwardly of the tuckers 204 and downfolding supports 205, and inwardly of the underfolding plows 207. Each such plow comprises an elongated L-shaped member consisting of a vertical leg 208 and a horizontal leg 209. Each of the horizontal legs 209 which extend toward each other, as shown in FIG. 2 have their edges inclined and converge toward each other from the end thereof, which initially receives the package, toward the end at which the package is conveyed onto the conveyor 276. Thus it will be evident that as the package moves along the length of the downfolder supports 205 and the plows 207, the ends of the wrapping material positioned therebetween will be caused to be folded under the package so that the underfolding step will have been completed by the time the package reaches the conveyor 276 where it is sealed.

The plates 206 on which the supports 205 are mounted are maintained to move in a vertical path by means of a secondary parallelogram comprising the rods 206a and 20Gb mounted at one end to the plate 206 and at their other ends on the frame. (FIGS. 1 and 2) The downfolder supports 205 are elevated and the package conveyed away therefrom to the sealing means by mechanism which may be more clearly understood by referring to said aforementioned patent. Briefly described, it will be noted that a shaft 210 extends between suitable bearing members on the spaced upper bars 79 of the parallelogram which operates the raising and lowering of the table 69. A sprocket 212 is mounted on the shaft 210 for rotation and supports a chain 213 which constitutes the outfeed conveyor. This chain also passes around another sprocket 214 mounted on the shaft 57 heretofore described. As the table 69 is moved between its lower and upper positions carrying with it the shaft 210, it will likewise carry one end of the outfeed conveyor, which is mounted thereon, through the sprocket 212,

A rod 215 also extends between the upper bars 79 of the parallelogram and moves upwardly and downwardly therewith. Each of the plates 206 has associated therewith a bumper 216 which may be seen in FIG. 1. As the bars 79 move to their uppermost position, they will carry the rod '215 therewith and eventually come against the bumpers 216 on the plates 206, thereupon elevating the plates and the downfolder supports 205 mounted thereon.

In this position the upper reach of the outfeed conveyor chain 213 is in a substantially horizontal position. The chain is moved by rotation of shaft 57 on which the sprocket 214 is mounted. This chain has a lug 217 thereon which is so positioned that upon the table reaching its uppermost position, it will come against what now has become the rear edge of the package and move it along the plows 209 and onto the conveyor 276.

Thus, at this point the package has had the front and rear tucks placed therein and the downfold, as well as the underfold performed thereon, so that the wrapping material is ready to be sealed. The sealing step and the construction of the sealing and shrinking means will now be described.

As mentioned hereinbefore, the material usually used to wrap packages in the machine to which the invention herein is to be applied, is heat sealable. A more recent improvement in heat-scalable wrapping material is the capability of the material to be shrunk about the package by the application of heat thereto. It is thus a primary feature of the invention herein to provide novel heat-sealing means to seal the underfolded ends of the wrapping material against the bottom of the package. A feature which may complement the heat sealing means is the provision of a heat tunnel or shrink tunnel through which the package may pass after the underfolded ends have been sealed, whereby the wrapping material may be shrunk about the package.

Reference has heretofore been made to the belt conveyor 276 which receives the package from the outfeed conveyor 213. This belt conveyor 276 has a plurality of spaced transversely extending pusher bars 277 throughout the length thereof secured to the belt and mounted at their ends onto the endless chains 278 and 279. These latter chains extend around sprockets on the ends of the two shafts 280 and 281. The shaft 280 is positioned adjacent the outfeed conveyor 213 and the other shaft 281 is located at the exit end of the heat tunnel 3 (FIG. 1). Thus, the conveyor carries the package over the heat sealer for the underfolded ends and through the heat tunnel if the wrapping material happens to be of a heat shrinkable character.

The belt conveyor 276 preferably has an intermittent movement. This in an important consideration particularly when a heat shrinkable material is used. The package when wrapped in such material must necessarily be subjected to a predetermined temperature for a predetermined time. The shorter the time, the higher the temperature must be, but high temperatures may tend to burn the material or discolor meat in the package. if the belt conveyor 276 were to be moved continuously, then the tunnel 3 would have to be comparatively long in order for the package to remain therein at a required low temperature for the required time. By moving the conveyor and package intermittently, the period of time that it is at rest within the tunnel is sufficient to cause the shrinking action at a low temperature and thus the tunnel can be considerably shortened.

The belt 276 is preferably formed of a thin flexible material and the upper reach thereof passes over heating elements, the details of which may be clearly seen by reference to FIGS. 3- 6. A pair of plates 294 and 295 are each provided with a plurality of longitudinally extending spaced upstanding ribs. These ribs on the plate 294 are indicated by the numeral 296 and those on the plate 295 are indicated by the numeral 297. Each plate 295 and 294 has positioned therebelow and in contact therewith the heating elements 298 and 299. When these heating elements are heated, they will elevate the temperature of the plates 294 and 295 and will heat the respective ribs 296 and 297.

An important feature of this aspect of the invention is the fact that the plates 294 and 295 are positioned in an inclined manner downwardly toward the center of the conveyor so that the innermost rib on each plate is lower than the outermost rib thereon. This is important from the standpoint that when the extending ends of the wrapping material are folded underneath the package along the bottom thereof, the layers of material will be thicker near the edges of the package and thinner toward the center of the package. This is because the material tends to fold upon itself so that the extreme ends of the material on the bottom of the package may have only one or two layers, whereas the material near the edges of the package will have several layers folded on top of each other. Thus, more heat and pressure will be required to seal the package near its edges than where the underfold terminates.

Thus, as shown for example in FIG. 27, the package P will have the outer edges thereof resting upon the uppermost edges of the ribs which incline downwardly therefrom so that nearer the center of the package the ribs will either not be in contact therewith, or the contact will be under relatively light pressure, as hereinafter described. Thus, heat and pressure are applied where it is needed most and the lesser heat is applied where it is needed less.

The provision of the ribs 296 and 297 also is for a definite purpose which relates to the heat-shrinkable film. When heat is applied to the bottom of the package, the material will shrink in the areas of heat application. Thus, if the heat is applied uniformly across the bottom, there will be no areas which will not tend to shrink, and therefore, of the material will shrink and may tear or break. On the other hand, with the use of the ribs, the material will shrink primarily in the areas where the ribs heat the film, thereby allowing those areas to shrink without breaking because there are intermediate areas of the unshrunk material.

Between the two plates 294 and 295 there is provided a channel member 300 having a bottom 301 and upstanding sides 302 and 303. The sides 302 and 303 have secured thereto the movable plates 304 and 305 which have a sliding movement up and down with respect to the channel 300. Each plate 304 is provided with a pin 306 which extends outwardly therefrom and rests upon a spring member 307. This wire spring 307 has one end mounted on a stud 308 and is biased upwardly at its free end against the associated pin 306, thereupon normally urging each of the plates 304 and 305 to an upper position. Pins 309 at each side limit the downward movement of the wire spring 307 and the plates 304 and 305.

THis arrangement is advantageous when wrapping packages formed of paper or cardboard trays where the bottom thereof tends to have an upwardly convex configuration. if all such packages were to be flat a cross the bottom, no problem of sealing would be encountered. However, the upwardly curved upper edges of the plates 304 and 305 will assure that even an upwardly convex bottom will be contacted by the heat of these center plates. These plates slide up and down under pressure of the spring 307 to accommodate packages, the bottoms of which may vary as to the degree of convexity. A heating element 310 (FIG. 6) is in contact with the underside of the channel member 300 to impart heat thereto, thereby to insure a thorough sealing of the entire bottom of the wrap.

The heat or shrink tunnel which has heretofore been identified by the numeral 3 in general is provided with a top 311 and downwardly extending sides 312 and 313 supported by frame members which extend longitudinally of the machine. This structure provides an enclosure through which the intermittently moving belt conveyor 276 moves and into which a portion of the heated plates 294 and 295 extend. As mentioned hereinbefore, air is blown into the tunnel through the flexible tube 72, which air is heated by any suitable electrical heating means.

As the wrapped package moves across the heat sealer, a yieldable pressure is applied thereto near the ends of the package. This is accomplished in the present machine by the use of a plurality of spring or yieldable ring members 316 at each side of the machine. There are two groups ofsuch yieldable members each mounted on a bar 317 at each side of the machine and which also are mounted to move toward and away from each other when adjustments are being made for packages of different widths.

These bars 317 extend rearwardly and each is pivoted at its rear end, as at 318, to a vertically extending side plate member 319 mounted on a suitable part of the machine which in turn is mounted in the transverse threaded rod 222 so that such plates may be moved toward and away from each other and carry with it the yieldable member 316.

These bars 317 and the yieldable member 316 mounted thereon are caused to be elevated as a package is being moved by the outfeed conveyor 213 onto the conveyor 276 and to thereafter move downwardly into contact with the package pressing the ends thereof against the heating elements as soon as the lowering table begins its downward movement. An understanding of the manner in which this is accomplished may be acquired by viewing the detailed view thereof shown in FIG. 2a.

Each bar 317 is provided'with a bearing block preferably formed of nylon or other suitable material indicated by the numeral 320 in FIG. 1. A crossbar 321 extends transversely of the conveyor upon which the bearing blocks 320 carrying the bars 317 may rest in the upper position thereof. Each end of the crossbar 321 is provided with a downwardly extending arm 322, the lower ends of which are secured to a plate 323 mounted at the opposite end thereof on the machine frame for pivotal or rocking movement, as at 324.

The upper bar 79 of the major parallelogram is provided with a stud 325 which extends outwardly therefrom and is adapted to come against the underside of plate 323 when the bar 79 is elevated as it raises the lowering table.

Since the package is moved along the plows onto the conveyor 276 simultaneously with movement of the next package to be wrapped from the platform 27 onto the lowering table, this table, as well as the bar 79 will be in their uppermost position. At this point the stud 325 will have rocked the plate 323 to that the free end thereof to which the crossbar 321 is secured by means of the arms 322, will have been elevated. During this elevation the crossbar 321 will come against the block 320 to elevate the yieldable members 316. A coiled tension spring 326 extends between the bar 317 and the plate 319 on which it is mounted, thereby to urge the yieldable members 316 downwardly against the package. When the lowering table and all of the parts associated therewith begin their downward movement, the crossbar 321 will also move downwardly and allow the yieldable member 316 to move down onto the package, thereby pressing it against the heating elements to insure a proper seal of the ends of the wrapping material against the bottom of the package.

As the package is pushed onto the receiving table 201, the opposite sides of the wrapping material are tucked along the ends of the package and the extending ends of the material beyond the package will have previously been folded partially downwardly. The remaining downfold of these extending ends of material is accomplished when the downfolder supports 205 raise the package upwardly off of the receiving table 201 and the outfeed conveyor moves it along the plows 209 to the heat-sealing station.

At this point the package is completely wrapped and it then is sealed along the bottom in the manner described above and the material is then. caused to shrink about the package as it passes through the heat tunnel, if the wrapping material is of the heat-shrinkable type.

Changes may be made in the form, construction and arrangement of parts from those disclosed herein without in any way departing from the spirit of the invention or sacrificing any of the attendant advantages thereof, provided, however, that such changes fall within the scope of the claims appended hereto.

1 claim:

1. In a wrapping machining wherein a web of heat scalable wrapping material is fed to a package-wrapping station and the wrapped package is conveyed therefrom to a heat sealing station, the improvement which comprises,

a. a heating element at said heat-sealing station having a concave surface transversely of the direction of movement of the package, to support flat-bottomed packages only adjacent their outermost edges where the layers of wrapping material are thicker and permit the center of the package to be spaced therefrom where the layers of wrapping material are thinner, and

b. a conveyor at said station for moving the package along the length of said heating element.

2. The combination of elements defined in claim 1, wherein said heating element includes a plurality of elongated upwardly projection ribs extending in the direction of movement of the package, the ribs inwardly of the outermost ribs along each side thereof each being at a progressively lower level, whereby less heat is applied to those portions of the package bottom inwardly of the sides thereof. a

3. The combination of elements defined in claim 1, wherein said conveyor comprises a flexible belt movable over said heating element and into contact therewith by the weight of the package thereon.

4. The combination of elements defined in claim 1, wherein said heating element includes two groups of upwardly projecting ribs and spaced apart at the center thereof, each group being inwardly and downwardly inclined, and a separate yieldably mounted heating element between said groups of heating elements.

5. The combination of elements defined in claim 2, wherein said ribs are in two spaced apart groups at opposite sides of the center of said conveyor, and a separate yieldably mounted heating element is located between said groups of ribs.

6. The combination of elements defined in claim 4, wherein said conveyor comprises a flexible belt movable over said heating element and into contact therewith by the weight of the package thereon. 

1. In a wrapping machining wherein a web of heat sealable wrapping material is fed to a package-wrapping station and the wrapped package is conveyed therefrom to a heat sealing station, the improvement which comprises, a. a heating element at said heat-sealing station having a concave surface transversely of the direction of movement of the package, to support flat-bottomed packages only adjacent their outermost edges where the layers of wrapping material are thicker and permit the center of the package to be spaced therefrom where the layers of wrapping material are thinner, and b. a conveyor at said station for moving the package along the length of said heating element.
 2. The combination of elements defined in claim 1, wherein said heating element includes a plurality of elongated upwardly projection ribs extending in the direction of movement of the package, the ribs inwardly of the outermost ribs along each side thereof each being at a progressively lower level, whereby less heat is applied to those portions of the package bottom inwardly of the sides thereof.
 3. The combination of elements defined in claim 1, wherein said conveyor comprises a flexible belt movable over said heating element and into contact therewith by the weight of the package thereon.
 4. The combination of elements defined in claim 1, wherein said heating element includes two groups of upwardly projecting ribs and spaced apart at the center thereof, each group being inwardly and downwardly inclined, and a separate yieldably mounted heating element between said groups of heating elements.
 5. The combination of elements defined in claim 2, wherein said ribs are in two spaced apart groups at opposite sides of the center of said conveyor, and a separate yieldably mounted heating element is located between said groups of ribs.
 6. The combination of elements defined in claim 4, wherein said conveyor comprises a flexible belt movable over said heating element and into contact therewith by the weight of the package thereon. 